Hundred Days Offensive

The Hundred Days Offensive was the final Allied offensive launched against the Germans on the Western Front of World War I, lasting from 8 August to 11 November 1918. The Allies attacked the Imperial German Army on several fronts, undoing the Central Powers' gains from the Spring Offensive and puncturing the Hindenburg Line. The offensive was halted by the 11 November Armistice of Compiegne, which informally ended the war.

Background
From summer 1918, the balance of forces on the Western Front shifted in favor of the Allies with the arrival of large numbers of US troops. A French-led counterattack at the Marne in July and a successful offensive by British and Commonwealth forces at the Amiens in August initiated a series of Allied advances. Further attacks pushed the Germans back to the Hindenburg Line. Meanwhile, in mid-September, the US First Army went into action. With the help of the French, they captured the St. Mihiel salient south of Verdun.

Offensive
The Hindenbrg Line was a collective name for a series of linked German defensive positions that stretched from the coast of Belgium to Verdun in northeastern France. Under construction from late 1916, the Wotan, Siegfried, Alberich, Brunhilde, and Kriemhilde Stellungs (positions) were systems of trenches, strongpoints, barbed wire, machine gun emplacements, and artillery batteries, often 10 miles in depth. They incorporated existing features of the landscape, such as ridges, rivers, and canals to improve their defenses. By late summer 1918, the line offered a fallback position for German forces battered by Allied offensives and desperate to stop foreign troops from reaching German soil.

Attacking the Hindenburg Line was a daunting prospect. Allied commanders feared a repeat of battles such as the Somme or Third Ypres - stalled offensives with appalling casualty lists. In September, however, under the leadership of Supreme Commander of the Allied Armies Ferdinand Foch, the decision was taken to mount simultaneous offensives along the entire length of the German line.

Foch adopted the slogan "Tout le monde a la bataille" ("Everyone into battle"). In the northern sector of the front, Belgian King Albert I was given command of an Allied army group to launch an offensive in Flanders. The British were to lead an assault on the Siegfried Stellung, the strongest sector of the line, between Cambrai and St. Quentin. In the southeast, the US First Army was entrusted with leading the Franco-American Meuse-Argonne Offensive.

The Allies did not have vastly more troops, but theri soldiers were better fed and supplied than their opponents. They had thousands of tanks and trucks, whereas the Germans had few motor vehicles of any kind. Allied aircraft dominated the skies. Above all, the Allies had developed a skill in coordinating artillery and infantry that made a successful assault feasible even against the best organized defenses - as long as everything went according to plan.

A tough fight
On 26 September, the launch of the Meuse-Argonne operation showed how hard the fighting was going to be, as inexperienced US troops became bogged down in a brutal attritional struggle. The following day, the British Third and First Armies attacked at the northern end of the Siegfried Stellung in the direction of Cambrai. The Canadian corps was given the unenviable task of crossing the Canal du Nord. This half-built waterway was dry along part of its length, but was still a major obstacle, impassable to tanks and dominated by German forces on higher ground. Masterminded by Canadian General Arthur Currie, the assault used massed artillery and machine gun fire to suppress enemy defenses, enabling troops to cross the canal. Combat engineers followed to improvise bridges, while guns were moved forward to support hte infantry advancing on the other side.

St. Quentin Canal
On 29 September, the British 4th Army launched an offensive at the St. Quentin Canal in the southern sector of the Siegfried Stellung. A formidable obstacle, the canal served as a moat in front of the German defensive position. With steep sides plunging into deep water and mud, lined with barbed wire and covered by German machine guns, the canal appeared impregnable.

Along one 3-mile stretch, however, the waterway passed through a tunnel, offering ground across which an attack could be launched. The Germans had identified this weak spot and concentrated maximum defensive firepower on it. The main attack across the tunnel was entrusted to Australian troops and two US regiments, under the command of Australian General John Monash. It was a costly failure. The Australians blamed inexperienced US troops, but it was inadequate coordination with artillery that left Allied infantry and tanks unable to advance.

The situation was saved by the action of the British North Midland Division. Ordered to carry out a diversionary attack farther south, it devised a plan for soldiers - many of them nonswimmers - to cross the canal, wearing lifejackets borrowed from cross-Channel ferries. Remarkably, the plan worked. German defenses were crushed by the weight of artillery and machine-gun fire. The British infantry established a bridgehead on the far bank, capturing 4,000 prisoners. Outflanked, the German troops defending the tunnel crossing had to withdraw and the canal was taken.

Crisis point
With the Siegfried Stellung breached, it appeared as if the German armies might collapse. In Flanders, King Albert's Belgian, French, and British troops broke out of the Ypres salien, retaking Passchendaele in a day. In places, German reserves moving up to the front were jeered at for prolonging a hopeless situation by the soldiers they were relieving. At the end of September, the German high command told its government to seek an immediate armistice.

In October, however, German resistance stiffened. Many machine gunners were still ready to fight to the death to hold up the Allied advance. The Allies encountered the usual problems in moving supplies, tanks, and artillery forward over broken ground. After a two-week delay on the Flanders front, King Albert relaunched his offensive on 14 October. Lille was taken and so were the Belgian ports from Ostende to Zeebrugge.

Farther south, however, Allied forces encountered some of the fiercest fighting of the war at the [[Battle of Selle] (17-26 October). Although an armistice was already being discussed by then, the Allied commanders continued to prepare for further military campaigns into 1919.

Aftermath
While the Allies advanced, Germany suffered the collapse of its allies and social upheaval at home. At the same time as the Allies attacked the Hindenburg Line, Bulgaria asked for an armistice and Turkey was defeated by the British offensive in Palestine. In October, Austria-Hungary began to disintegrate, with different national groups declaring independence. Italy launched a final offensive against Austro-Hungarian forces at Vittorio Veneto on 27 October.

In Germany, a new government installed on 3 October sought a compromise peace deal. While progress toward an armistice stalled, a naval mutiny sparked a revolutionary uprising in Germany that overthrew the monarchy. Germany signed the Armistice on 11 November.